Table 1.

Characteristics of study participants: mutagen sensitivity assay and genetic association study.

Variables	Cohort members with methylation results	Mutagen sensitivity assay			Genetic association study
Variables	Cohort members with methylation results	Cases	Controls	P value	Cases	Controls	P value
Total	824	77	78		131	130
Age at enrollment, mean ± SD	56.7 ± 9.7	59.6 ± 9.2	55.1 ± 9.4	0.003^*	57.2 ± 9.9	55.0 ± 9.7	0.067^*
< 51 (%)	33	22	38	0.005^†	31	38	0.104^†
51−63	38	34	41		37	41
≥ 63	29	44	21		32	21
Gender (%)
Female	79	62	62	0.918^†	72	72	0.921^†
Male	21	38	38		28	28
Race (%)
Non-Hispanic White	76	74	73	0.510^†	76	77	0.733^†
Hispanic	17	17	22		18	18
Others	6	9	5		7	5
Smoking history
Current (%)	55	47	63	0.045^†	49	57	0.172^†
Pack years, mean ± SD	40.5 ± 21.5	42.8 ± 25.0	39.5 ± 22.6	0.393^*	42.2 ± 24.3	40.4 ± 21.4	0.524^*
Duration, mean ± SD	33.7 ± 9.7	33.4 ± 9.7	32.6 ± 8.9	0.569^*	33.3 ± 9.9	32.9 ± 9.4	0.804^*
Chronic airway obstruction (%)^‡	26	36	26	0.181^†	36	32	0.458^†
Spontaneous chromatid breaks/cell, mean ± SD	—	0.013 ± 0.015	0.021 ± 0.025	0.085^§

Two-sided two-sample t test between cases (methylated group) and controls (unmethylated group).

^†

χ² test for differences between cases and controls.

^‡

Chronic airway obstruction is defined as post-bronchodilator FEV1/FVC % < 70%.

^§

Two-sided Wilcoxon rank sum test between cases and controls.